


Cheesy Kinktober

by Nenchen



Category: Undertale (Video Game)
Genre: Multi
Language: English
Status: Completed
Published: 2018-10-04
Updated: 2018-10-04
Packaged: 2019-07-25 07:02:37
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 1,914
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16192514
Author URL: https://archiveofourown.org/users/Nenchen/pseuds/Nenchen
Summary: Me (at this moment still trying to) doing Kinktober! I got some requests over tumblr and will try to fill in the rest.Expect: smut and fluff/comedy. I just can't do only smut. The kinks and pairings of each chapter are in the chapter summaries!





	1. Rusty trombone tango

**Author's Note:**

> Underfell: Male Frisk x Sans.  
> Frisk is still nonbinary and mute.   
> Kink: deep throating, face sitting

It had been years since they left the underground. Years since the kid had broken the barrier and freed them all, and years since mosters had become somewhat integrated into human society. Years since the kid had been an actual kid, they were 25 now. But not years, not even a month since monster -human “reproductive” relationships had been deemed safe and legalized by their governments. Sans could only guess what kind of fun Alphys had had with those experiments.

He had gotten the news by Frisk barging into his room and straight up taking their shirt off. Bold and determined as always, they had started kissing him, pushing him into his mattress as they wiggled their hands underneath his jacket.

“woah hey kid what’s gotten into ya?” he had asked, nervously sweating below them. They had agreed having this kind of intimate relationship was too dangerous to pursue with all of the unknown factors of magic body parts and human sensitive areas, not to mention the way monsters would use their soul… just too much risk for someone you loved. They had settled for kissing, well nuzzling, some really creative things with toys or without touching each other at all to satisfy their needs enough until then.

*Didn’t you hear?* Frisk had signed, beaming at him. *Alphys’ research is done. Touching is safe. SEX is safe! Even souls are!*  
When his only response had been to stare up at them, completely still for a minute, they had gotten worried and poked his cheek, which resulted in him tackling them down and a quick, but heated make out session, ending with their souls intertwined for hours. He had to promise buying his brother sound-proof earphones after that one, but it had been so worth it.  
Since Sans didn’t have the necessary parts they had stayed with soul sex for the following days, slowly exploring each others bodies with their hands.  
He had already found out how much Frisk liked having certain parts of their body played with, the sudden waves of pleasure leaving them both spent, and him with cum on his shirt. But yesterday he had found out something exiting.  
While watching a romance movie with Frisk, they saw a passionate French kiss scene, and his mind went astray.  
‘man, that looks fun. wish we could do that, bet Frisk would make the most delicious faces…’ he had thought. And his magic had reacted to his lust, his intent, and formed something in his mouth. Things went very nicely according to plan after that, even though Frisk hadn’t been that surprised by him just making something appear since the whoopee-cushion-in-the-hand stunt he had pulled on them all those years ago.

Today, sadly they had an important meeting as the ambassador they couldn’t skip, so the both of them had to put off having fun until the evening. But Red already had a plan. Why not find out how to use this new appendage to his advantage and their shared pleasure? The human undernet would surely have some ideas for him.

A few hours and a few searches of the “How to use your tongue to pleasure your boyfriend” kind later, he was ready. He felt prepared for a whole new kind of experience, and his magic was already thrumming excitedly.  
When he heard their key turning in the lock he quickly got into his pose. Good thing Boss had very loudly announced that he would be staying over at Undynes today. That was not something you accidentally wanted to surprise your little brother with, he thought while putting his foot up the chair he had gotten as a prop.  
Frisk opened the door, went in and…  
Nearly died from laughing. Welp, he guessed he could still surprise them a lot after all. They clearly hadn‘t been expecting a naked skeleton in Captain Morgan pose with a cheap fake rose between his teeth and suggestive wiggling browbones.  
Still doubled over from their laughing fit they signed *WHAT THE HECK SANS*, only to clutch their stomach again afterwards.  
„what. it’s the naked man. internet says you got a one third chance of gettin laid after pulling this one, and ya know me im all about that low effort.“  
*That’s what they said? I think they were pulling your leg.* Frisk signed, still breathing heavy.  
„welp. doesn’t matter, now, does it? i got another thing in store for that.“, He answered, winking at them just before slowly dragging his freshly formed tongue over his teeth.  
„c’mere sweetheart.“  
Frisk obliged happily, strutting in front of him while pulling their Shirt over their head, which left him face to abs. Undynes workout plan really was no joke, he thought absentmindedly as they leaned down to kiss him. He melted into the kiss and their embrace, tongues tasting each other, hands exploring and undressing desperately. Frisk let out a low moan as he connected their souls, giving him a confused look when he pushed them off.  
“aww pumpkin, did ya think that was all i found during all of the hours you’ve been gone? honestly you should know a science nerd like me does research thoroughly.”, he purred, getting down on his knees. And before they could even begin to question him, he cut them off by taking their erect dick into his mouth in its entirety. The sudden, intense wave on pleasure he felt through their bond floored him, quite literally. He could feel his legs giving out under him, making his mouth pop off their dick. Frisk, to be fair, didn’t fare much better.  
“wow, heh, i read that this deep throating thing is like the number one thing for humans but fuckin hell hon. didn’t think i could make you fall for me any more than you already were.”  
Frisk chuckled at that one, lightly punching his shoulder and signing, *And since when do YOU have a throat? How, what, WHY?*  
He got up on his knees again, slowly dragging his fingers up their thighs, massaging closely to the base of their cock as he answered. “always had one, my treat. how else did ya think I didn’t make a complete mess while eatin?”, he asked, grinning up at them to see them rolling their eyes and signing *But you ARE always doing that!*  
He winked at them, shrugging and answering nonchalantly “welp, maybe i just like makin messes. i surely enjoy making one out of you.” right before taking them back into his mouth. Going slower this time he used his tongue to tease them, to draw out the small, nearly silent sounds that were only for him. They were grabbing onto his skull, hands feverishly wandering to his shoulders, his spine, his ahhh fuck, he could feel them getting worked up so much quicker than normal. He hadn’t even noticed how deep he had taken them, he just knew how good he was making them feel when his throat constricted around them, trying reflexively to swallow the object on his mouth. They were so close to an orgasm, he could feel their muscles tightening under his hands, their breathing getting heavier… and that’s when he decided to stop. Slowly, still teasing them with his tongue, he moved off, giving the tip a last lick before stopping entirely. A frustrated noise made him look up. “patience cutie. found something else i wanna try with this tongue if ya don’t mind?” He inquired. Their eyes widened for a second, and he could feel anticipation and excitement through their bond as they nodded. Yes.  
He wasted no time getting behind them, one hand closing around their neglected dick, while he gave them a first, tentative lick. The way their breath caught in their throat told him all he needed to know, and soon he was pumping them in the front and straight up eating them out in the back. His tongue was teasing their sensitive spots, moving inside as he chased those breathy moans, the quiver of their thighs when he made them feel so good they had troubles staying upright. At some point his free hand had grabbed them to stabilize them, and now he was using this to get as close as possible, to get them closer until they couldn’t take it anymore. Throwing their head back, mouth open in a silent scream of pleasure, hitting both of them like shockwaves until they were both laying on the ground, heaving and spent.  
Dazed, he felt Frisk getting up, lifting him into the air and dragging the both of them on the couch, curling around him. He lazily used his magic to pull a blanket over them, and this is how they stayed for what seemed like an hour, getting back on the ground. It was Sans who finally broke the comfy silence to mumble “m really glad ya liked that last thing that much. picked it for the name.” The following questioning huff made him chuckle.  
“rusty trombone.”


	2. Talking out of your ass

**Notes for the Chapter:**

> Undertale Sans x Underswap Papyrus (Stonerbros)  
> !Drug use mentioned!  
> Kink: ass worship

„whoaaaa.“, Stretch marveled. „just like a lava lamp.“ He poked Sans' right cheek and watched, mesmerized as the lighter and darker swirls of his magic started to react and formed spirals around his finger. The closer he looked the more different shades he could make out. It was at least a hundred shades of blue. „heh dude i wanna see too! take a vid of my magic butt swirls!“ Sans laughed.

„you mean of your bubble behind? the great magic vortex of your buttocks? your ass-io the fantastico?“, Stretch chuckled as he got out his phone. After that last one Sans couldn’t hold himself together anymore and got a laughing fit. Stretch chuckled some more while taking another deep breath of the dog treat. What was he supposed to do again? Ah, right, Butt movie. Sans‘ laughter made him shake it too hard to film though.

„hey bud could you stop laughing your ass off for a sec? else how am i supposed to show you the great beyond?“, he joked. Which of course didn’t help Sans laughing fit at all. But how could he stop him? All he could think off right now were butt puns about those hot buns.  
Not knowing how else to help himself he just grabbed a handful of magic and squeezed while starting the camera. Sans butt didn’t just look nice, it also felt nice, he thought while kneading his handful of butt.

„dude you can kiss my ass.“ Sans retorted. Hm, looks like he thought out loud again instead of silent. Welp. „ok“, he said before learning forwards, nuzzling his face into that heavenly soft magic. Good thing that Sans wasn’t as bony as him. Heh. He was kneading Sans‘ ass with both of his hands now, while resting his head on there. So soft. He could’ve easily been lulled to sleep by the comfiness and soft glow of the ever-changing Spirals, if he hadn’t heard the soft moan the other let out.  
A devious grin spread on his face as he started to knead the cheeks more earnestly.

„heh, you’re a cheeky fuck, aren’t you?“, Sans moaned.

„i dont know what else you asspected bud.“, Stretch answered, grinning.

„after all i’m really…“, he paused as he softly bit down on one cheek, „a pain in the ass.“

Sans let out a string of soft curses as Stretch licked over the mark and then moved on to circle his butthole. „fuck me.“, he swore softly.

„i’ll be right happy to.“


End file.
